Paper sheet supplying apparatus and image forming apparatus provided with the same

ABSTRACT

There is described a paper sheet supplying apparatus that supplies paper sheets one by one to the image forming apparatus and conducts the dehumidifying operation of paper sheets only when a specific kind of paper sheets are accommodated in the paper sheet accommodating section, so as to achieve a high operating efficiency. The paper sheet supplying apparatus includes: a paper sheet accommodating section to accommodate paper sheets; a paper sheet feeding section to feed the paper sheets one by one from the paper sheet accommodating section; a dehumidification dryer to dehumidify the paper sheet accommodating section; and a control section to control the dehumidification dryer. Only when the control section receives paper kind information representing a specific kind of paper sheet, the control section activates and controls the dehumidification dryer, based on the paper kind information.

This application is based on Japanese Patent Application No. 2006-108395filed on Apr. 11, 2006 with Japan Patent Office, the entire content ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a paper sheet supplying apparatus forsupplying paper sheets one by one into an image forming apparatus, etc.,and also relates to an image forming apparatus provided with the papersheet supplying apparatus.

When a paper sheet, on which an image is to be formed, absorbs moisture,various problems, such as inability of reproducing an image having adesired image quality, a stability degradation of the paper feedingoperation, etc., have occurred. To solve such the problem, PatentDocuments 1 and 2 (Tokkai 2000-255807 and Tokkai 2005-335837, both areJapanese Non-Examined Patent Publications) set forth a solving method,which includes the steps of: detecting the humidity in the vicinity ofthe paper sheet supplying apparatus; estimating the rate of moistureabsorption of the paper sheet concerned, based on the detected result;activating the dehumidification dryer, such as a heater, a dry airblower, etc., based on the estimated rate of moisture absorption, so asto dehumidify the paper sheet concerned.

In the conventional countermeasures for moisture absorption problem ofthe paper sheets, including the abovementioned method set forth inPatent Documents 1 and 2 (Tokkai 2000-255807 and Tokkai 2005-335837,both are Japanese Non-Examined Patent Publications), such thecountermeasures have been applied to all kinds of paper sheets.

When dehumidifying a paper sheet, it is necessary or desirable to stopthe paper sheet feeding operation during the moisture absorbingoperation of the paper sheet concerned. This is because, in theapparatus which is designed to conduct the dehumidifying operation whenthe paper sheet absorbs moisture, a conveyance error or a degradation ofthe image quality is liable to occur, if the paper sheet is conveyed andthe image forming operation is conducted in the mid-course of themoisture absorbing operation at which the rate of moisture absorption ofthe paper sheet concerned has not decreased to the allowable value.

The problems with respect to the image forming apparatus, caused by themoisture absorption of the paper sheet, include a paper sheet conveyanceproblem and an image quality problem. Since a part of the paper sheetconveyance problem and the image quality problem can be solved byimproving the conveyance mechanism, by adjusting the image formingprocess, etc., even when the paper sheet absorbs moisture, it is notnecessary to conduct the moisture absorbing operation for every time. Onthe other hand, since it is difficult to solve a problem of a separationerror, caused by the moisture absorption of the paper sheet in theseparating process in which a single paper sheet is separated and pickedup from a large number of paper sheets accommodated in a paper sheetsaccommodating section, by improving the conveyance mechanism, etc., itis indispensable to conduct the moisture absorbing operation as acountermeasure to cope with the separation error mentioned in the above.

Further, as a result of the intensive study conducted by the presentinventor, it has been revealed that the abovementioned separation errorin the paper sheet feeding process occurs for a specific kind of papersheet to be used, instead of occurring for all kinds of paper sheets tobe used.

Specifically, with respect to enamel paper sheets, such as art papers,coated papers, etc., when the paper sheets absorb moisture, since theseparation error is liable to occur due to the sticking phenomenonbetween the paper sheets stacked into the paper sheet accommodatingsection, the moisture absorbing operation becomes necessary. However,with respect to other kinds of paper sheets, it has been revealed thatthe moisture absorbing operation is not necessary, since the separationerror hardly occur, even when the paper sheets absorb moisture.Accordingly, the present inventor has found that, by applying themoisture absorbing operation only to such the specific kind of papersheet, it becomes possible to eliminate the separation error, which isliable to occur in the paper sheet feeding process, and therefore, itbecomes possible to avoid the problem caused by the moisture absorptionof paper sheets.

As aforementioned, conventionally, the moisture absorbing operation hasbeen applied to all kinds of paper sheets, when the moisture absorptionof the paper sheets is detected. Accordingly, there has been a problemthat the efficiency of the apparatus is lowered due to the lengthywaiting time for stopping the apparatus to conduct the moistureabsorbing operation for every kind of paper sheet. Specifically, since atotal time period for forming images on the normal paper sheets occupiesmost of all operating time of the image forming apparatus, there hasbeen a problem that a substantial operating efficiency of the imageforming apparatus is considerably deteriorated, when the waiting timefor stopping the apparatus to conduct the moisture absorbing operationis introduced even in such the image forming operation that uses thenormal paper sheets.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a paper sheet supplyingapparatus comprises: a paper sheet accommodating section to accommodatepaper sheets; a paper sheet feeding section to feed the paper sheets oneby one from the paper sheet accommodating section; a dehumidificationdryer to dehumidify the paper sheet accommodating section; and a controlsection to control the dehumidification dryer; wherein, only when thecontrol section receives paper kind information representing a specifickind of paper sheet, the control section activates and controls thedehumidification dryer, based on the paper kind information.

According to another aspect of the present invention, an image formingsystem comprises: an image forming apparatus to form an image on a papersheet; and a paper sheet supplying apparatus to supply the paper sheetto the image forming apparatus; wherein the paper sheet supplyingapparatus includes: a paper sheet accommodating section to accommodatepaper sheets; a paper sheet feeding section to feed the paper sheets oneby one from the paper sheet accommodating section; a dehumidificationdryer to dehumidify the paper sheet accommodating section; and a controlsection to control the dehumidification dryer; wherein, only when thecontrol section receives paper kind information representing a specifickind of paper sheet, the control section activates and controls thedehumidification dryer, based on the paper kind information.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described, by way of example only, withreference to the accompanying drawings which are meant to be exemplary,not limiting, and wherein like elements are numbered alike in severalFigures, in which:

FIG. 1 shows a brief configuration of an image forming apparatusembodied in the present invention;

FIG. 2 shows a cross sectional schematic diagram of the paper sheetfeeding apparatus;

FIG. 3( a) and FIG. 3( b) show perspective views of a paper sheetfeeding tray serving as a paper sheet feeding apparatus embodied in thepresent invention;

FIG. 4 shows a block diagram of a dehumidification control system forconducting a dehumidifying operation; and

FIG. 5 shows a flowchart of controlling operations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, the embodiments of the present invention willbe detailed in the following. However, the scope of the presentinvention is not limited to the embodiments described in the following.

FIG. 1 shows a brief configuration of an image forming apparatusembodied in the present invention.

The image forming apparatus is constituted by an image forming apparatusproper GH and a mass-storage paper sheet supplying apparatus LT, servingas a paper sheet supplying apparatus embodied in the present invention.

The image forming apparatus proper GH, called a tandem-type color imageforming apparatus, is constituted by a plurality of image formingsections 10Y, 10M, 10C, 10K, a belt-type intermediate transfer member 6,a paper sheet feeding section 20, a fixing device 30, etc.

The image forming apparatus proper GH is provided with an image readingsection A disposed on its upper side. An image of a document placed on aplaten glass is exposed by scanning a light beam emitted from a documentimage exposure—scanning device equipped in the image reading section A,so that a line image sensor reads the image of the document. Analogueimage signals generated by the photoelectric converting actionsperformed in the line image sensor are inputted into an image processingsection, in order to apply various kinds of image processing, such as ananalogue processing, an analogue-to-digital conversion processing, ashading correction processing, etc., to the inputted analogue imagesignals. Then, the digital image data generated from the analogue imagesignals are inputted into an exposing section 3.

Each of the image forming sections 10Y, 10M, 10C, 10K for formingunicolor images of colors Y (Yellow), M (Magenta), C (Cyan), K (Black),respectively, is provided with a photoreceptor drum 1, a chargingsection 2, the exposing section 3, a developing section 4, a cleaningsection 5 and a primary transferring section 7. In FIG. 1, the referencenumbers are only attached to the sections included in the image formingsection 10Y, and with respect to the image forming sections 10M, 10C,10K, the reference numbers are omitted.

The belt-type intermediate transfer member 6 is threaded on a pluralityof rollers, so as to circulate along the plurality of image formingsections 10Y, 10M, 10C, 10K.

The unicolor toner images of colors Y (Yellow), M (Magenta), C (Cyan), K(Black) respectively formed by the plurality of image forming sections10Y, 10M, 10C, 10K are sequentially transferred one by one onto thebelt-type intermediate transfer member 6 currently circulating along theplurality of image forming sections 10Y, 10M, 10C, 10K (primarytransferring operation) by the primary transferring sections 7,respectively, in such a manner that the unicolor images are superimposedwith each other so as to form a full color toner image.

A paper sheet S, accommodated in a paper sheet feeding cassette 21A of apaper sheet supplying section 20, is picked up by a paper sheet feedingsection 22A and conveyed to a secondary transferring section 9 by pairsof paper sheet feeding rollers 23, 24, 25, 26, a pair of registrationroller 27, etc. Then, the full color toner image formed on the belt-typeintermediate transfer member 6 is further transferred onto the papersheet S by the secondary transferring section 9 (secondary transferringoperation).

Incidentally, since the paper sheet feeding cassettes, aligned in avertical direction as three stages, have substantially the samestructure, the same reference number of 21A is attached to each of them.Further, since the paper sheet feeding sections also have substantiallythe same structure, the same reference number of 22A is attached to eachof them.

The paper sheet S, having the full color toner image transferred on it,is tightly griped by a pair of a heating roller 30A and a pressingroller 30B equipped in the fixing device 30, so as to apply heat andpressure onto the paper sheet S. As a result of this action, the fullcolor toner image residing on the paper sheet S is fixed onto the papersheet S. Then, the paper sheet S is tightly griped by a pair of ejectingrollers 28 so as to eject and stack it onto an ejecting tray 29 disposedoutside the apparatus.

On the other hand, after the full color toner image is transferred ontothe paper sheet S by the secondary transferring section 9 and the papersheet S is peeled off the belt-type intermediate transfer member 6 by acurvature separating action, the belt-type intermediate transfer member6 is cleaned by a cleaning device 8.

When the paper sheet S, having the fixed full color toner image is to beejected in a reverse ejecting mode, the paper sheet S passes through aconveyance path located at the lower side of a switching gate 28A inFIG. 1 so that the paper sheet S is conveyed into a first conveyancepath r1 extended toward the bottom of the apparatus. Then, theconveyance direction of the paper sheet S is switched to the reversedirection, so that the paper sheet S passes through a second conveyancepath r2 located at the left side of the switching gate 28A in FIG. 1.Successively, the paper sheet S is tightly griped by the pair ofejecting rollers 28 and ejected outside the apparatus.

When the duplex image forming mode in which the toner images are formedon the both sides of the paper sheet S is to be performed, after thefull color toner image formed on the first side of the paper sheet S isfixed onto the paper sheet S, the paper sheet S is conveyed into thefirst conveyance path r1 and further conveyed into a third conveyancepath r3. Then, the conveyance direction of the paper sheet S is switchedto the reverse direction, so that the paper sheet S is conveyed into afourth conveyance path r4, serving as a detour path toward the upperdirection, and further conveyed by the pair of paper sheet feedingrollers 26. Successively, through the same process as mentioned in theabove, another full color toner image is transferred onto a second sideof the paper sheet S, being a reverse side of the first side, and fixedonto the paper sheet S by applying heat and pressure onto both the fullcolor toner image and the paper sheet S in the fixing device 30, andthen, the paper sheet S having the fixed toner image is ejected outsidethe apparatus.

Incidentally, although the image forming apparatus proper GH describedin the foregoing is an image forming apparatus for forming a full colorimage, it is needless to say that the present invention can be alsoapplied for an image forming apparatus for forming a monochrome image.

The mass-storage paper sheet supplying apparatus LT for supplying alarge number of paper sheets, for instance, more than 1000 paper sheets,is coupled to the right side surface of the image forming apparatusproper GH.

The mass-storage paper sheet supplying apparatus LT is provided with apaper sheet feeding tray 100A and a paper sheet feeding tray 100B, whichserves as two-stage paper sheet accommodating sections divided intoupper and lower stages.

A paper sheet feeding unit 103A picks up and separates a single papersheet, namely, a paper sheet S, from paper sheets stacked on the papersheet feeding tray 100A located at the upper stage. Then, pairs ofconveyance rollers 104, 105 conveys the paper sheet S into the imageforming apparatus proper GH through the pair of paper sheet feedingroller 24.

A paper sheet feeding unit 103B picks up and separates a single papersheet, namely, a paper sheet S, from paper sheets stacked on the papersheet feeding tray 100B located at the lower stage. Then, the pair ofconveyance rollers 105 conveys the paper sheet S into the image formingapparatus proper GH through the pair of paper sheet feeding roller 24.

Each of numeral 108A and 108B indicates a paper sheet stacking plate onwhich the paper sheets S are stacked. Each of the paper sheet stackingplates 108A, 108B elevates in response to an upper surface detectingsignal outputted from a paper sheet sensor 120 for detecting theuppermost surface of the stacked paper sheets S, so as to keep a heightof the uppermost surface of the stacked paper sheets S constant,irrespective of a number of paper sheets currently stacked, as detailedlater.

Each of numeral SW1 and SW2 indicates a switching unit serving as amount/demount detecting element for detecting whether each of the papersheet feeding tray 100A and the paper sheet feeding tray 100B is mountedor demounted into/from the mass-storage paper sheet supplying apparatusLT.

Referring to FIG. 2 and FIG. 3, the paper sheet feeding trays 100A, 100Bwill be detailed in the following. Incidentally, in the description inthe following, since the structures of the paper sheet feeding trays100A, 100B are the same as each other, the alphabetical symbols A and Bto be attached to the reference numbers will be omitted. For instance,as shown in FIG. 2, each of the paper sheet feeding trays 100A, 100B issimply indicated by a paper sheet feeding tray 100, and has theconfiguration and the function as detailed in the following so as toindependently perform the dehumidifying operation described as follow.

FIG. 2 shows a cross sectional schematic diagram of the paper sheetfeeding apparatus, while FIG. 3( a) and FIG. 3( b) show perspectiveviews of the paper sheet feeding tray 100 serving as the paper sheetfeeding apparatus embodied in the present invention.

FIG. 3( a) shows a perspective view of a main section of the paper sheetfeeding tray 100 in such a state that a cover is removed from the papersheet feeding tray 100, while FIG. 3( b) shows a perspective view of aheight detecting section for detecting the uppermost surface of thestacked paper sheets.

As shown in FIG. 3( a), the paper sheets S are stacked on a paper sheetstacking plate 108 (equivalent to each of the paper sheet stackingplates 108A, 108B shown in FIG. 1) and movably supported in such amanner that a bunch of the paper sheets S can be elevated or descendedby an elevating/descending mechanism (not shown in the drawings). A pairof side regulating members 111, 112, serving as a paper sheetedge-portion regulating member, is movable in both a conveyancedirection of the paper sheet S (Y-axis direction shown in FIG. 3) and awidth direction intersecting the Y-axis (X-axis direction shown in FIG.3), so as to contact the both edge sides of the paper sheet S toregulate the both side positions of the paper sheet S. A trailing edgeregulating member 118 is also movable in the conveyance direction of thepaper sheet S (Y-axis direction shown in FIG. 3) so as to regulate thetrailing edge position of the paper sheet S, and also serves as a papersheet edge-portion regulating member. A paper sheet feeding unit 103 isdisposed at the leading edge-portion of the paper sheet S in theconveyance direction of the paper sheet S, and a delivery roller 103 aof the paper sheet feeding unit 103 contacts an uppermost paper sheet Sawhile pressing the uppermost paper sheet Sa with an appropriatepressure.

The positions of the pair of side regulating members 111, 112 and thetrailing edge regulating member 118 are regulated (adjusted),corresponding to a size of the paper sheet to be employed.

When the delivery roller 103 a rotates in a direction indicated by arrowa1, the uppermost paper sheet Sa progresses in the Y-axis directionindicated by arrow Y, and then, is separated into a single paper sheetby a separating unit including a separating roller 103 b and a reverseroller 103 c, and conveyed to a pair of conveyance rollers 104.

In order to detect a height of the uppermost surface of the stackedpaper sheets, the paper sheet sensor 120 shown in FIG. 3( b) isprovided. The paper sheet sensor 120 is constituted by a detecting arm121 having a hole shaped in an elliptical and arcuate ring into which ashaft 103 ax of the delivery roller 103 a is inserted in a freelymovable state, a rotating shaft 103 bx for supporting the detecting arm121 in a freely rotatable state, a shading plate 122 fixed onto thepaper sheet sensor 120 and a photo-coupler 123 disposed in such a mannerthat a top portion of the shading plate 122 can be freely inserted intoa gap between a photo-receiving port and a photo-emitting port of thephoto-coupler 123. The separating roller 103 b is rotated by the drivingforce of the rotating shaft 103 bx. Since the detecting arm 121 isheavier than the shading plate 122, the detecting arm 121 always keepscontacting the uppermost surface of the stacked paper sheets S with alittle pressure. According as a level of the surface of the uppermostpaper sheet Sa descends due to a reduction of the number of stackedpaper sheets as a result of the paper sheet feeding operation, the topportion of the detecting arm 121 is gradually lowered, and, at the sametime, the top portion of the shading plate 122 swings out of the gap ofthe photo-coupler 123. As a result, since the photo-receiving port ofthe photo-coupler 123 receives a light emitted from the photo-emittingport of the same, the fact that the level of the surface of theuppermost paper sheet Sa descends can be detected. Then, theelevating/descending mechanism (not shown in the drawings) is activatedto elevate the paper sheet stacking plate 108, so that the level of thesurface of the uppermost paper sheet Sa is elevated to a position atwhich the top portion of the shading plate 122 again shades the lightemitted from the photo-emitting port of the photo-coupler 123. When thepaper sheet sensor 120 detects the fact that the level of the surface ofthe uppermost paper sheet Sa reaches a predetermined position, theelevating/descending mechanism is deactivated.

According to the abovementioned operation, it becomes possible to alwayskeep the height of the upper surface of the paper sheet S, namely, thelevel of the surface of the uppermost paper sheet Sa, constant. Thescope of a structure of the paper sheet sensor 120 is not limited tothat shown in FIG. 3( a). Any other structure capable of detecting aposition of the upper surface of the paper sheet is applicable in thepresent invention.

The dehumidification dryer shown in FIG. 2 includes a air blower forblowing air against the paper sheets accommodated in the paper sheetfeeding tray 100 and a heater for heating the air so as to decrease therelative humidity of the air.

An air duct 113, which is provided with an air intake inlet 113Adisposed at its upper section and an air exhaust outlet 113B disposed atits lower section, is equipped on the side surface of the paper sheetfeeding tray 100, while a heater 114 is mounted inside the air duct 113.

Further, a side regulating member 111 is shaped in a vertically lengthybox, and provided with an air exhaust outlet 111A disposed at its uppersection, an air intake inlet 111B disposed at its lower section and afan 116 disposed at its lower section.

Still further, a side regulating member 112 is shaped in a verticallylengthy box, and provided with an air exhaust outlet 112A disposed atits upper section, an air intake inlet 112B disposed at its lowersection and a fan 117 disposed at its lower section.

By activating a fan 115, the fan 116 and the fan 117, the air circulatesinside the paper sheet feeding tray 100 according to the arrowsindicated in FIG. 2, and the dry air dehumidified by the heating actionof the heater 114 is blown against the paper sheets S stacked on thepaper sheet stacking plate 108.

Since the air is brown against the upper portion of the stacked papersheets, the air also has a role for separating a single paper sheet formthe stacked paper sheets, in order to help the separating operation tobe conducted by the pair of separating roller 103 b and the reverseroller 103 c and to securely achieve the single paper separatingoperation.

Further, by blowing the dried air, the relative humidity of which isdecreased by the heating action of the heater 114, against the stackedpaper sheets, the dehumidifying operation for reducing a moisturecontent included in the paper sheet S can be conducted.

Although the dehumidification dryer, which blows the dried air againstthe paper sheets, is exemplified in the foregoing, any one ofconventional dehumidification dryers, such as a dryer that is providedwith a heater disposed at its lower side to heat and dehumidify thepaper sheet, a dehumidification dryer that performs both the heatingoperation of the paper sheet and the blowing operation of the dried air,etc., can be employed in the embodiment of the present invention.

FIG. 4 shows a block diagram of the dehumidification control system forconducting the dehumidifying operation.

In the embodiment of the present invention, based on informationrepresenting a kind of paper sheets (hereinafter, referred to as paperkind information) sent from a paper kind setting section SK, only whenenamel paper sheets, such as art papers, coated papers, etc., are loadedin the paper sheet feeding tray 100, a control section CR activates adehumidification dryer HC to conduct the dehumidifying operation of thepaper sheets accommodated in the paper sheet accommodating section.

An operating section of the image forming apparatus includes the paperkind setting section SK, so that paper kind information are inputtedinto the control section CR, when the operator sets a kind of papersheets to be accommodated in the paper sheet accommodating section. Inaddition, at the time when the operator selects and draws out the papersheet feeding tray either 100A or 100B, the switching unit either SW1 orSW2, serving as the mount/demount detecting switch, is turned ON so asto designate the paper sheet feeding tray either 100A or 100B. Then, thecontrol section CR receives information indicating that paper sheets ofthe specific kind set by the operator are loaded into the paper sheetfeeding tray either 100A or 100B.

A humidity sensor HS is attached to an outer wall of the image formingapparatus. Since a rate of moisture absorption of the paper sheet,accommodated in the supplemental paper sheet accommodating sectioninstalled outside the image forming apparatus, substantially correspondsto a humidity of the outside air, the rate of moisture absorption of thepaper sheets to be loaded can be estimated by detecting the humidity ofthe outside air with the humidity sensor HS.

Further, based on outside humidity information sent from the humiditysensor HS serving as a humidity detecting element, the control sectionCR determines whether or not the dehumidifying operation should beconducted and sets a duration time for the dehumidifying operation,corresponding to the rate of moisture absorption of the paper sheets tobe loaded.

Still further, based on a paper-sheet differential residual amountdetected from the difference between a residual amount of paper sheetsremaining in the paper sheet accommodating section before the papersheet loading operation and that after the paper sheet loadingoperation, the control section CR not only can determine whether or notthe dehumidifying operation should be conducted, but also can set theduration time for the dehumidifying operation based on the residualamount of paper sheets.

Correlation between the humidity and the duration time of thedehumidifying operation, and correlation between the residual amount ofpaper sheets and the duration time of the dehumidifying operation arefound from the experiments in advance, and a operating time table ofthem are stored in a storage section MR in advance.

FIG. 5 shows a flowchart of the controlling operations to be conductedby the control section CR, described in the foregoing.

As aforementioned, the control section CR receives the paper kindinformation sent from the paper kind setting section SK (Step S1) todetermine whether or not the concerned paper sheets are enamel papersheets (Step S2). When determining that the concerned paper sheets arenot enamel paper sheets (Step S3; No), the control section CR finalizesthe operation (END).

When determining that the concerned paper sheets are enamel paper sheets(Step S3; Yes), the control section CR receives residual amountinformation sent from a paper-sheet residual amount detecting section PD(Step S4). The paper-sheet residual amount detecting section PD detectsthe height of the paper sheet stacking plate 108 shown in FIG. 2, andderives the paper-sheet residual amount information from a number ofrotations of a motor (not shown in the drawings) for driving the papersheet stacking plate 108.

When the paper-sheet residual amounts before and afterdemounting/mounting operations of the paper sheet feeding tray 100,namely, before drawing it and after reloading it, differ from eachother, it can be determined that additional paper sheets are newlyloaded into the paper sheet feeding tray 100. While, when thepaper-sheet residual amounts before and after demounting/mountingoperations do not differ from each other, it can be determined that thedemounting/mounting operations are conducted without loading additionalpaper sheets.

Accordingly, when determining that the paper-sheet residual amountsbefore and after demounting/mounting operations are the same (Step S5;No), the control section CR finalizes the operation (END).

On the other hand, when determining that the paper-sheet residualamounts before and after demounting/mounting operations differ from eachother (Step S5; Yes), the control section CR reads the output value ofthe humidity sensor HS (Step S6).

The presence or absence of the change of paper-sheet residual amount canbe detected by employing the information sent from the paper-sheetresidual amount detecting section PD and the other information sent fromthe switching units SW1, SW2.

Concretely speaking, a paper-sheet residual amount before drawing thepaper sheet feeding tray 100 is detected by employing information sentfrom the paper-sheet residual amount detecting section PD before drawingit, a mount/demount status of the paper sheet feeding tray 100 isdetected by employing information sent from the switching units SW1,SW2, and a paper-sheet residual amount after mounting the paper sheetfeeding tray 100 is detected by employing information sent from thepaper-sheet residual amount detecting section PD after mounting it.Then, by comparing the paper-sheet residual amount before drawing withthat after mounting, the presence or absence of the change ofpaper-sheet residual amount can be detected.

When the output value of the humidity sensor HS, namely, the humidity ofoutside air, is a sufficiently low value to such an extent that thedehumidifying operation is not necessary (Step S7; No), the controlsection CR finalizes the operation (END). On the other hand, when theoutput value of the humidity sensor HS indicates a necessity of thedehumidifying operation (Step S7; Yes), the control section CRimplements the dehumidifying operation of the paper sheets S (Step S8).

Concretely speaking, to implement the dehumidifying operation of thepaper sheets S, the control section CR not only activates the fan 115,the fan 116 and the fan 117, but also drives the heater 114 so as tocirculate the dried air around the inside of the paper sheet feedingtray 100 (Step S8).

At the time when the dehumidifying operation is commenced, the controlsection CR immediately bans the paper sheet feeding operation during thedehumidifying operation (Step S8).

The control section CR reads the table of dehumidifying duration time soas to select an appropriate duration time corresponding to the humidityof outside air. Table 1 is an example of the table of dehumidifyingduration time.

The control section CR deactivates the dehumidifying operation, justafter the selected duration time has elapsed, and removes the ban on thepaper sheet feeding operation to finalize the operation.

TABLE 1 Duration time of Humidity of dehumidifying outside air Targettemperature in tray activation ≦55% No dehumidifying operation 0 56–60%“Temperature of outside air” +6° 6 minutes 61–65% “Temperature ofoutside air” +7° 7 minutes 66–70% “Temperature of outside air” +8° 8minutes 71–75% “Temperature of outside air” +9° 9 minutes ≧76%“Temperature of outside air” +10° 10 minutes

The control section CR deactivates the dehumidifying operation, justafter each of the duration times indicated in Table 1 has elapsed, andremoves the ban on the paper sheet feeding operation (Step S9) tofinalize the operation (END).

Incidentally, although the two-stage controlling operation correspondingto the presence or absence of the change of paper-sheet residual amountis conducted in the example shown in FIG. 5, it is also applicable that,by reading a duration time of dehumidifying operation corresponding tothe paper-sheet residual amount from the storage section MR, thedehumidifying operation is conducted during the time intervalcorresponding to the paper-sheet residual amount.

According to the present invention, since the dehumidifying operation isconducted only when a specific kind of paper sheets are accommodated inthe paper sheet accommodating section, even if the paper sheet feedingoperation is deactivated during the dehumidifying operation, thereduction rate of the image forming efficiency is kept at a low level.Accordingly, it becomes possible to provide a paper sheet supplyingapparatus having a high operating efficiency, and therefore, it alsobecomes possible to provide an image forming apparatus to be operated ata high efficiency.

Specifically, since no deactivation of the image-forming operation dueto the dehumidifying operation of the recording materials occurs duringthe image forming operation employing normal paper sheets whose usagefrequency is normally high, it becomes possible to drastically improveits practical operating efficiency.

While the preferred embodiments of the present invention have beendescribed using specific term, such description is for illustrativepurpose only, and it is to be understood that changes and variations maybe made without departing from the spirit and scope of the appendedclaims.

1. A paper sheet supplying apparatus, comprising: a paper sheetaccommodating section to accommodate paper sheets; a paper sheet feedingsection to feed the paper sheets one by one from the paper sheetaccommodating section; a dehumidification dryer to dehumidify the papersheet accommodating section; and a control section to control thedehumidification dryer; wherein, only when the control section receivespaper kind information representing a specific kind of paper sheet, thecontrol section activates and controls the dehumidification dryer, basedon the paper kind information.
 2. The paper sheet supplying apparatus ofclaim 1, further comprising: an outside humidity detecting member todetect a humidity of air outside the paper sheet supplying apparatus;wherein the control section activates and controls the dehumidificationdryer, based on the humidity detected by the outside humidity detectingmember.
 3. The paper sheet supplying apparatus of claim 1, furthercomprising: a paper-sheet residual amount detecting section to detect aresidual amount of paper sheets remaining in the paper sheetaccommodating section; and a mount/dismount detecting member to detect amounting or dismounting status of the paper sheet accommodating section;wherein the control section activates and controls the dehumidificationdryer, when the residual amount of paper sheets, detected by thepaper-sheet residual amount detecting section, changes before and afterthe mount/dismount detecting member detects the dismounting and mountingstatus of the paper sheet accommodating section.
 4. The paper sheetsupplying apparatus of claim 1, further comprising: a storage section tostore at least an operating time table in which an amount of papersheets accommodated in the paper sheet accommodating section iscorrelated with an activating time of the dehumidification dryer;wherein the control section controls the activating time of thedehumidification dryer, based on change of a residual amount of papersheets remaining in the paper sheet accommodating section.
 5. The papersheet supplying apparatus of claim 1, further comprising: a storagesection to store at least an operating time table in which a humidity ofair outside the paper sheet supplying apparatus is correlated with anactivating time of the dehumidification dryer; wherein the controlsection controls the activating time of the dehumidification dryer,based on the humidity of the air outside the paper sheet supplyingapparatus.
 6. The paper sheet supplying apparatus of claim 1, whereinthe control section bans a paper sheet feeding operation to be conductedby the paper sheet feeding section, during an activating time of thedehumidification dryer.
 7. The paper sheet supplying apparatus of claim1, wherein, only when the paper kind information represents an enamelpaper sheet as the specific kind of paper sheet, the control sectionactivates and controls the dehumidification dryer, based on the paperkind information.
 8. The paper sheet supplying apparatus of claim 1,wherein the dehumidification dryer is provided with a blower section toblow dry air against the paper sheets accommodate in the paper sheetaccommodating section from a side edge direction of the paper sheets. 9.The paper sheet supplying apparatus of claim 8, wherein the blowersection includes a heater to heat air, an air exhaust outlet to blow offthe air heated by the heater against an upper portion of the papersheets stacked on the paper sheet accommodating section and a fan toblow off the air heated by the heater from the air exhaust outlet. 10.An image forming system, comprising: an image forming apparatus to forman image on a paper sheet; and a paper sheet supplying apparatus tosupply the paper sheet to the image forming apparatus; wherein the papersheet supplying apparatus includes: a paper sheet accommodating sectionto accommodate paper sheets; a paper sheet feeding section to feed thepaper sheets one by one from the paper sheet accommodating section; adehumidification dryer to dehumidify the paper sheet accommodatingsection; and a control section to control the dehumidification dryer;wherein, only when the control section receives paper kind informationrepresenting a specific kind of paper sheet, the control sectionactivates and controls the dehumidification dryer, based on the paperkind information.
 11. The image forming system of claim 10, wherein thepaper sheet supplying apparatus further includes: an outside humiditydetecting member to detect a humidity of air outside the paper sheetsupplying apparatus; wherein the control section activates and controlsthe dehumidification dryer, based on the humidity detected by theoutside humidity detecting member.
 12. The image forming system of claim10, wherein the paper sheet supplying apparatus further includes: apaper-sheet residual amount detecting section to detect a residualamount of paper sheets remaining in the paper sheet accommodatingsection; and a mount/dismount detecting member to detect a mounting ordismounting status of the paper sheet accommodating section; wherein thecontrol section activates and controls the dehumidification dryer, whenthe residual amount of paper sheets, detected by the paper-sheetresidual amount detecting section, changes before and after themount/dismount detecting member detects the dismounting and mountingstatus of the paper sheet accommodating section.
 13. The image formingsystem of claim 10, wherein the paper sheet supplying apparatus furtherincludes: a storage section to store at least an operating time table inwhich an amount of paper sheets accommodated in the paper sheetaccommodating section is correlated with an activating time of thedehumidification dryer; wherein the control section controls theactivating time of the dehumidification dryer, based on change of aresidual amount of paper sheets remaining in the paper sheetaccommodating section.
 14. The image forming system of claim 10, whereinthe paper sheet supplying apparatus further includes: a storage sectionto store at least an operating time table in which a humidity of airoutside the paper sheet supplying apparatus is correlated with anactivating time of the dehumidification dryer; wherein the controlsection controls the activating time of the dehumidification dryer,based on the humidity of the air outside the paper sheet supplyingapparatus.
 15. The image forming system of claim 10, wherein the controlsection bans a paper sheet feeding operation to be conducted by thepaper sheet feeding section, during an activating time of thedehumidification dryer.
 16. The image forming system of claim 10,wherein, only when the paper kind information represents an enamel papersheet as the specific kind of paper sheet, the control section activatesand controls the dehumidification dryer, based on the paper kindinformation.
 17. The image forming system of claim 10, wherein thedehumidification dryer is provided with a blower section to blow dry airagainst the paper sheets accommodate in the paper sheet accommodatingsection from a side edge direction of the paper sheets.
 18. The imageforming system of claim 17, wherein the blower section includes a heaterto heat air, an air exhaust outlet to blow off the air heated by theheater against an upper portion of the paper sheets stacked on the papersheet accommodating section and a fan to blow off the air heated by theheater from the air exhaust outlet.